// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ALSA sequencer Client Manager
 *  Copyright (c) 1998-2001 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                             Jaroslav Kysela <perex@perex.cz>
 *                             Takashi Iwai <tiwai@suse.de>
 */

#include <linux/init.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <linux/kmod.h>

#include <sound/seq_kernel.h>
#include <sound/ump.h>
#include "seq_clientmgr.h"
#include "seq_memory.h"
#include "seq_queue.h"
#include "seq_timer.h"
#include "seq_info.h"
#include "seq_system.h"
#include "seq_ump_convert.h"
#include <sound/seq_device.h>
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
#endif

/* Client Manager

 * this module handles the connections of userland and kernel clients
 * 
 */

/*
 * There are four ranges of client numbers (last two shared):
 * 0..15: global clients
 * 16..127: statically allocated client numbers for cards 0..27
 * 128..191: dynamically allocated client numbers for cards 28..31
 * 128..191: dynamically allocated client numbers for applications
 */

/* number of kernel non-card clients */
#define SNDRV_SEQ_GLOBAL_CLIENTS	16
/* clients per cards, for static clients */
#define SNDRV_SEQ_CLIENTS_PER_CARD	4
/* dynamically allocated client numbers (both kernel drivers and user space) */
#define SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN	128

#define SNDRV_SEQ_LFLG_INPUT	0x0001
#define SNDRV_SEQ_LFLG_OUTPUT	0x0002
#define SNDRV_SEQ_LFLG_OPEN	(SNDRV_SEQ_LFLG_INPUT|SNDRV_SEQ_LFLG_OUTPUT)

static DEFINE_SPINLOCK(clients_lock);
static DEFINE_MUTEX(register_mutex);

/*
 * client table
 */
static char clienttablock[SNDRV_SEQ_MAX_CLIENTS];
static struct snd_seq_client *clienttab[SNDRV_SEQ_MAX_CLIENTS];
static struct snd_seq_usage client_usage;

/*
 * prototypes
 */
static int bounce_error_event(struct snd_seq_client *client,
			      struct snd_seq_event *event,
			      int err, int atomic, int hop);
static int snd_seq_deliver_single_event(struct snd_seq_client *client,
					struct snd_seq_event *event,
					int atomic, int hop);

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
static void free_ump_info(struct snd_seq_client *client);
#endif

/*
 */
static inline unsigned short snd_seq_file_flags(struct file *file)
{
        switch (file->f_mode & (FMODE_READ | FMODE_WRITE)) {
        case FMODE_WRITE:
                return SNDRV_SEQ_LFLG_OUTPUT;
        case FMODE_READ:
                return SNDRV_SEQ_LFLG_INPUT;
        default:
                return SNDRV_SEQ_LFLG_OPEN;
        }
}

static inline int snd_seq_write_pool_allocated(struct snd_seq_client *client)
{
	return snd_seq_total_cells(client->pool) > 0;
}

/* return pointer to client structure for specified id */
static struct snd_seq_client *clientptr(int clientid)
{
	if (clientid < 0 || clientid >= SNDRV_SEQ_MAX_CLIENTS) {
		pr_debug("ALSA: seq: oops. Trying to get pointer to client %d\n",
			   clientid);
		return NULL;
	}
	return clienttab[clientid];
}

static struct snd_seq_client *client_use_ptr(int clientid, bool load_module)
{
	struct snd_seq_client *client;

	if (clientid < 0 || clientid >= SNDRV_SEQ_MAX_CLIENTS) {
		pr_debug("ALSA: seq: oops. Trying to get pointer to client %d\n",
			   clientid);
		return NULL;
	}
	scoped_guard(spinlock_irqsave, &clients_lock) {
		client = clientptr(clientid);
		if (client)
			return snd_seq_client_ref(client);
		if (clienttablock[clientid])
			return NULL;
	}
#ifdef CONFIG_MODULES
	if (load_module) {
		static DECLARE_BITMAP(client_requested, SNDRV_SEQ_GLOBAL_CLIENTS);
		static DECLARE_BITMAP(card_requested, SNDRV_CARDS);

		if (clientid < SNDRV_SEQ_GLOBAL_CLIENTS) {
			int idx;
			
			if (!test_and_set_bit(clientid, client_requested)) {
				for (idx = 0; idx < 15; idx++) {
					if (seq_client_load[idx] < 0)
						break;
					if (seq_client_load[idx] == clientid) {
						request_module("snd-seq-client-%i",
							       clientid);
						break;
					}
				}
			}
		} else if (clientid < SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN) {
			int card = (clientid - SNDRV_SEQ_GLOBAL_CLIENTS) /
				SNDRV_SEQ_CLIENTS_PER_CARD;
			if (card < snd_ecards_limit) {
				if (!test_and_set_bit(card, card_requested))
					snd_request_card(card);
				snd_seq_device_load_drivers();
			}
		}
		scoped_guard(spinlock_irqsave, &clients_lock) {
			client = clientptr(clientid);
			if (client)
				return snd_seq_client_ref(client);
		}
	}
#endif
	return NULL;
}

/* get snd_seq_client object for the given id quickly */
struct snd_seq_client *snd_seq_client_use_ptr(int clientid)
{
	return client_use_ptr(clientid, false);
}

/* get snd_seq_client object for the given id;
 * if not found, retry after loading the modules
 */
static struct snd_seq_client *client_load_and_use_ptr(int clientid)
{
	return client_use_ptr(clientid, IS_ENABLED(CONFIG_MODULES));
}

static void usage_alloc(struct snd_seq_usage *res, int num)
{
	res->cur += num;
	if (res->cur > res->peak)
		res->peak = res->cur;
}

static void usage_free(struct snd_seq_usage *res, int num)
{
	res->cur -= num;
}

/* initialise data structures */
int __init client_init_data(void)
{
	/* zap out the client table */
	memset(&clienttablock, 0, sizeof(clienttablock));
	memset(&clienttab, 0, sizeof(clienttab));
	return 0;
}


static struct snd_seq_client *seq_create_client1(int client_index, int poolsize)
{
	int c;
	struct snd_seq_client *client;

	/* init client data */
	client = kzalloc(sizeof(*client), GFP_KERNEL);
	if (client == NULL)
		return NULL;
	client->pool = snd_seq_pool_new(poolsize);
	if (client->pool == NULL) {
		kfree(client);
		return NULL;
	}
	client->type = NO_CLIENT;
	snd_use_lock_init(&client->use_lock);
	rwlock_init(&client->ports_lock);
	mutex_init(&client->ports_mutex);
	INIT_LIST_HEAD(&client->ports_list_head);
	mutex_init(&client->ioctl_mutex);
	client->ump_endpoint_port = -1;

	/* find free slot in the client table */
	scoped_guard(spinlock_irq, &clients_lock) {
		if (client_index < 0) {
			for (c = SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN;
			     c < SNDRV_SEQ_MAX_CLIENTS;
			     c++) {
				if (clienttab[c] || clienttablock[c])
					continue;
				clienttab[client->number = c] = client;
				return client;
			}
		} else {
			if (clienttab[client_index] == NULL && !clienttablock[client_index]) {
				clienttab[client->number = client_index] = client;
				return client;
			}
		}
	}

	snd_seq_pool_delete(&client->pool);
	kfree(client);
	return NULL;	/* no free slot found or busy, return failure code */
}


static int seq_free_client1(struct snd_seq_client *client)
{
	if (!client)
		return 0;
	scoped_guard(spinlock_irq, &clients_lock) {
		clienttablock[client->number] = 1;
		clienttab[client->number] = NULL;
	}
	snd_seq_delete_all_ports(client);
	snd_seq_queue_client_leave(client->number);
	snd_use_lock_sync(&client->use_lock);
	if (client->pool)
		snd_seq_pool_delete(&client->pool);
	scoped_guard(spinlock_irq, &clients_lock) {
		clienttablock[client->number] = 0;
	}
	return 0;
}


static void seq_free_client(struct snd_seq_client * client)
{
	scoped_guard(mutex, &register_mutex) {
		switch (client->type) {
		case NO_CLIENT:
			pr_warn("ALSA: seq: Trying to free unused client %d\n",
				client->number);
			break;
		case USER_CLIENT:
		case KERNEL_CLIENT:
			seq_free_client1(client);
			usage_free(&client_usage, 1);
			break;

		default:
			pr_err("ALSA: seq: Trying to free client %d with undefined type = %d\n",
			       client->number, client->type);
		}
	}

	snd_seq_system_client_ev_client_exit(client->number);
}



/* -------------------------------------------------------- */

/* create a user client */
static int snd_seq_open(struct inode *inode, struct file *file)
{
	int c, mode;			/* client id */
	struct snd_seq_client *client;
	struct snd_seq_user_client *user;
	int err;

	err = stream_open(inode, file);
	if (err < 0)
		return err;

	scoped_guard(mutex, &register_mutex) {
		client = seq_create_client1(-1, SNDRV_SEQ_DEFAULT_EVENTS);
		if (!client)
			return -ENOMEM;	/* failure code */

		mode = snd_seq_file_flags(file);
		if (mode & SNDRV_SEQ_LFLG_INPUT)
			client->accept_input = 1;
		if (mode & SNDRV_SEQ_LFLG_OUTPUT)
			client->accept_output = 1;

		user = &client->data.user;
		user->fifo = NULL;
		user->fifo_pool_size = 0;

		if (mode & SNDRV_SEQ_LFLG_INPUT) {
			user->fifo_pool_size = SNDRV_SEQ_DEFAULT_CLIENT_EVENTS;
			user->fifo = snd_seq_fifo_new(user->fifo_pool_size);
			if (user->fifo == NULL) {
				seq_free_client1(client);
				kfree(client);
				return -ENOMEM;
			}
		}

		usage_alloc(&client_usage, 1);
		client->type = USER_CLIENT;
	}

	c = client->number;
	file->private_data = client;

	/* fill client data */
	user->file = file;
	sprintf(client->name, "Client-%d", c);
	client->data.user.owner = get_pid(task_pid(current));

	/* make others aware this new client */
	snd_seq_system_client_ev_client_start(c);

	return 0;
}

/* delete a user client */
static int snd_seq_release(struct inode *inode, struct file *file)
{
	struct snd_seq_client *client = file->private_data;

	if (client) {
		seq_free_client(client);
		if (client->data.user.fifo)
			snd_seq_fifo_delete(&client->data.user.fifo);
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
		free_ump_info(client);
#endif
		put_pid(client->data.user.owner);
		kfree(client);
	}

	return 0;
}

static bool event_is_compatible(const struct snd_seq_client *client,
				const struct snd_seq_event *ev)
{
	if (snd_seq_ev_is_ump(ev) && !client->midi_version)
		return false;
	if (snd_seq_ev_is_ump(ev) && snd_seq_ev_is_variable(ev))
		return false;
	return true;
}

/* handle client read() */
/* possible error values:
 *	-ENXIO	invalid client or file open mode
 *	-ENOSPC	FIFO overflow (the flag is cleared after this error report)
 *	-EINVAL	no enough user-space buffer to write the whole event
 *	-EFAULT	seg. fault during copy to user space
 */
static ssize_t snd_seq_read(struct file *file, char __user *buf, size_t count,
			    loff_t *offset)
{
	struct snd_seq_client *client = file->private_data;
	struct snd_seq_fifo *fifo;
	size_t aligned_size;
	int err;
	long result = 0;
	struct snd_seq_event_cell *cell;

	if (!(snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_INPUT))
		return -ENXIO;

	if (!access_ok(buf, count))
		return -EFAULT;

	/* check client structures are in place */
	if (snd_BUG_ON(!client))
		return -ENXIO;

	if (!client->accept_input)
		return -ENXIO;
	fifo = client->data.user.fifo;
	if (!fifo)
		return -ENXIO;

	if (atomic_read(&fifo->overflow) > 0) {
		/* buffer overflow is detected */
		snd_seq_fifo_clear(fifo);
		/* return error code */
		return -ENOSPC;
	}

	cell = NULL;
	err = 0;
	guard(snd_seq_fifo)(fifo);

	if (IS_ENABLED(CONFIG_SND_SEQ_UMP) && client->midi_version > 0)
		aligned_size = sizeof(struct snd_seq_ump_event);
	else
		aligned_size = sizeof(struct snd_seq_event);

	/* while data available in queue */
	while (count >= aligned_size) {
		int nonblock;

		nonblock = (file->f_flags & O_NONBLOCK) || result > 0;
		err = snd_seq_fifo_cell_out(fifo, &cell, nonblock);
		if (err < 0)
			break;
		if (!event_is_compatible(client, &cell->event)) {
			snd_seq_cell_free(cell);
			cell = NULL;
			continue;
		}
		if (snd_seq_ev_is_variable(&cell->event)) {
			struct snd_seq_ump_event tmpev;

			memcpy(&tmpev, &cell->event, aligned_size);
			tmpev.data.ext.len &= ~SNDRV_SEQ_EXT_MASK;
			if (copy_to_user(buf, &tmpev, aligned_size)) {
				err = -EFAULT;
				break;
			}
			count -= aligned_size;
			buf += aligned_size;
			err = snd_seq_expand_var_event(&cell->event, count,
						       (char __force *)buf, 0,
						       aligned_size);
			if (err < 0)
				break;
			result += err;
			count -= err;
			buf += err;
		} else {
			if (copy_to_user(buf, &cell->event, aligned_size)) {
				err = -EFAULT;
				break;
			}
			count -= aligned_size;
			buf += aligned_size;
		}
		snd_seq_cell_free(cell);
		cell = NULL; /* to be sure */
		result += aligned_size;
	}

	if (err < 0) {
		if (cell)
			snd_seq_fifo_cell_putback(fifo, cell);
		if (err == -EAGAIN && result > 0)
			err = 0;
	}

	return (err < 0) ? err : result;
}


/*
 * check access permission to the port
 */
static int check_port_perm(struct snd_seq_client_port *port, unsigned int flags)
{
	if ((port->capability & flags) != flags)
		return 0;
	return flags;
}

/*
 * check if the destination client is available, and return the pointer
 */
static struct snd_seq_client *get_event_dest_client(struct snd_seq_event *event)
{
	struct snd_seq_client *dest __free(snd_seq_client) =
		snd_seq_client_use_ptr(event->dest.client);

	if (dest == NULL)
		return NULL;
	if (! dest->accept_input)
		return NULL;
	if (snd_seq_ev_is_ump(event))
		return no_free_ptr(dest); /* ok - no filter checks */

	if ((dest->filter & SNDRV_SEQ_FILTER_USE_EVENT) &&
	    ! test_bit(event->type, dest->event_filter))
		return NULL;

	return no_free_ptr(dest); /* ok - accessible */
}


/*
 * Return the error event.
 *
 * If the receiver client is a user client, the original event is
 * encapsulated in SNDRV_SEQ_EVENT_BOUNCE as variable length event.  If
 * the original event is also variable length, the external data is
 * copied after the event record. 
 * If the receiver client is a kernel client, the original event is
 * quoted in SNDRV_SEQ_EVENT_KERNEL_ERROR, since this requires no extra
 * kmalloc.
 */
static int bounce_error_event(struct snd_seq_client *client,
			      struct snd_seq_event *event,
			      int err, int atomic, int hop)
{
	struct snd_seq_event bounce_ev;
	int result;

	if (client == NULL ||
	    ! (client->filter & SNDRV_SEQ_FILTER_BOUNCE) ||
	    ! client->accept_input)
		return 0; /* ignored */

	/* set up quoted error */
	memset(&bounce_ev, 0, sizeof(bounce_ev));
	bounce_ev.type = SNDRV_SEQ_EVENT_KERNEL_ERROR;
	bounce_ev.flags = SNDRV_SEQ_EVENT_LENGTH_FIXED;
	bounce_ev.queue = SNDRV_SEQ_QUEUE_DIRECT;
	bounce_ev.source.client = SNDRV_SEQ_CLIENT_SYSTEM;
	bounce_ev.source.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;
	bounce_ev.dest.client = client->number;
	bounce_ev.dest.port = event->source.port;
	bounce_ev.data.quote.origin = event->dest;
	bounce_ev.data.quote.event = event;
	bounce_ev.data.quote.value = -err; /* use positive value */
	result = snd_seq_deliver_single_event(NULL, &bounce_ev, atomic, hop + 1);
	if (result < 0) {
		client->event_lost++;
		return result;
	}

	return result;
}


/*
 * rewrite the time-stamp of the event record with the curren time
 * of the given queue.
 * return non-zero if updated.
 */
static int update_timestamp_of_queue(struct snd_seq_event *event,
				     int queue, int real_time)
{
	struct snd_seq_queue *q __free(snd_seq_queue) =
		queueptr(queue);

	if (! q)
		return 0;
	event->queue = queue;
	event->flags &= ~SNDRV_SEQ_TIME_STAMP_MASK;
	if (real_time) {
		event->time.time = snd_seq_timer_get_cur_time(q->timer, true);
		event->flags |= SNDRV_SEQ_TIME_STAMP_REAL;
	} else {
		event->time.tick = snd_seq_timer_get_cur_tick(q->timer);
		event->flags |= SNDRV_SEQ_TIME_STAMP_TICK;
	}
	return 1;
}

/* deliver a single event; called from below and UMP converter */
int __snd_seq_deliver_single_event(struct snd_seq_client *dest,
				   struct snd_seq_client_port *dest_port,
				   struct snd_seq_event *event,
				   int atomic, int hop)
{
	switch (dest->type) {
	case USER_CLIENT:
		if (!dest->data.user.fifo)
			return 0;
		return snd_seq_fifo_event_in(dest->data.user.fifo, event);
	case KERNEL_CLIENT:
		if (!dest_port->event_input)
			return 0;
		return dest_port->event_input(event,
					      snd_seq_ev_is_direct(event),
					      dest_port->private_data,
					      atomic, hop);
	}
	return 0;
}

/* deliver a single event; called from snd_seq_deliver_single_event() */
static int _snd_seq_deliver_single_event(struct snd_seq_client *client,
					 struct snd_seq_event *event,
					 int atomic, int hop)
{
	struct snd_seq_client *dest __free(snd_seq_client) =
		get_event_dest_client(event);
	if (dest == NULL)
		return -ENOENT;

	struct snd_seq_client_port *dest_port __free(snd_seq_port) =
		snd_seq_port_use_ptr(dest, event->dest.port);
	if (dest_port == NULL)
		return -ENOENT;

	/* check permission */
	if (!check_port_perm(dest_port, SNDRV_SEQ_PORT_CAP_WRITE))
		return -EPERM;

	if (dest_port->timestamping)
		update_timestamp_of_queue(event, dest_port->time_queue,
					  dest_port->time_real);

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
	if (snd_seq_ev_is_ump(event)) {
		if (!(dest->filter & SNDRV_SEQ_FILTER_NO_CONVERT))
			return snd_seq_deliver_from_ump(client, dest, dest_port,
							event, atomic, hop);
		else if (dest->type == USER_CLIENT &&
			 !snd_seq_client_is_ump(dest))
			return 0; // drop the event
	} else if (snd_seq_client_is_ump(dest)) {
		if (!(dest->filter & SNDRV_SEQ_FILTER_NO_CONVERT))
			return snd_seq_deliver_to_ump(client, dest, dest_port,
						      event, atomic, hop);
	}
#endif /* CONFIG_SND_SEQ_UMP */

	return __snd_seq_deliver_single_event(dest, dest_port, event,
					      atomic, hop);
}

/*
 * deliver an event to the specified destination.
 * if filter is non-zero, client filter bitmap is tested.
 *
 *  RETURN VALUE: 0 : if succeeded
 *		 <0 : error
 */
static int snd_seq_deliver_single_event(struct snd_seq_client *client,
					struct snd_seq_event *event,
					int atomic, int hop)
{
	int result = _snd_seq_deliver_single_event(client, event, atomic, hop);

	if (result < 0 && !snd_seq_ev_is_direct(event))
		return bounce_error_event(client, event, result, atomic, hop);
	return result;
}


/*
 * send the event to all subscribers:
 */
static int __deliver_to_subscribers(struct snd_seq_client *client,
				    struct snd_seq_event *event,
				    int port, int atomic, int hop)
{
	struct snd_seq_subscribers *subs;
	int err, result = 0, num_ev = 0;
	union __snd_seq_event event_saved;
	size_t saved_size;
	struct snd_seq_port_subs_info *grp;

	if (port < 0)
		return 0;

	struct snd_seq_client_port *src_port __free(snd_seq_port) =
		snd_seq_port_use_ptr(client, port);
	if (!src_port)
		return 0;

	/* save original event record */
	saved_size = snd_seq_event_packet_size(event);
	memcpy(&event_saved, event, saved_size);
	grp = &src_port->c_src;
	
	/* lock list */
	if (atomic)
		read_lock(&grp->list_lock);
	else
		down_read_nested(&grp->list_mutex, hop);
	list_for_each_entry(subs, &grp->list_head, src_list) {
		/* both ports ready? */
		if (atomic_read(&subs->ref_count) != 2)
			continue;
		event->dest = subs->info.dest;
		if (subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIMESTAMP)
			/* convert time according to flag with subscription */
			update_timestamp_of_queue(event, subs->info.queue,
						  subs->info.flags & SNDRV_SEQ_PORT_SUBS_TIME_REAL);
		err = snd_seq_deliver_single_event(client, event, atomic, hop);
		if (err < 0) {
			/* save first error that occurs and continue */
			if (!result)
				result = err;
			continue;
		}
		num_ev++;
		/* restore original event record */
		memcpy(event, &event_saved, saved_size);
	}
	if (atomic)
		read_unlock(&grp->list_lock);
	else
		up_read(&grp->list_mutex);
	memcpy(event, &event_saved, saved_size);
	return (result < 0) ? result : num_ev;
}

static int deliver_to_subscribers(struct snd_seq_client *client,
				  struct snd_seq_event *event,
				  int atomic, int hop)
{
	int ret;
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
	int ret2;
#endif

	ret = __deliver_to_subscribers(client, event,
				       event->source.port, atomic, hop);
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
	if (!snd_seq_client_is_ump(client) || client->ump_endpoint_port < 0)
		return ret;
	/* If it's an event from EP port (and with a UMP group),
	 * deliver to subscribers of the corresponding UMP group port, too.
	 * Or, if it's from non-EP port, deliver to subscribers of EP port, too.
	 */
	if (event->source.port == client->ump_endpoint_port)
		ret2 = __deliver_to_subscribers(client, event,
						snd_seq_ump_group_port(event),
						atomic, hop);
	else
		ret2 = __deliver_to_subscribers(client, event,
						client->ump_endpoint_port,
						atomic, hop);
	if (ret2 < 0)
		return ret2;
#endif
	return ret;
}

/* deliver an event to the destination port(s).
 * if the event is to subscribers or broadcast, the event is dispatched
 * to multiple targets.
 *
 * RETURN VALUE: n > 0  : the number of delivered events.
 *               n == 0 : the event was not passed to any client.
 *               n < 0  : error - event was not processed.
 */
static int snd_seq_deliver_event(struct snd_seq_client *client, struct snd_seq_event *event,
				 int atomic, int hop)
{
	int result;

	hop++;
	if (hop >= SNDRV_SEQ_MAX_HOPS) {
		pr_debug("ALSA: seq: too long delivery path (%d:%d->%d:%d)\n",
			   event->source.client, event->source.port,
			   event->dest.client, event->dest.port);
		return -EMLINK;
	}

	if (snd_seq_ev_is_variable(event) &&
	    snd_BUG_ON(atomic && (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR)))
		return -EINVAL;

	if (event->queue == SNDRV_SEQ_ADDRESS_SUBSCRIBERS ||
	    event->dest.client == SNDRV_SEQ_ADDRESS_SUBSCRIBERS)
		result = deliver_to_subscribers(client, event, atomic, hop);
	else
		result = snd_seq_deliver_single_event(client, event, atomic, hop);

	return result;
}

/*
 * dispatch an event cell:
 * This function is called only from queue check routines in timer
 * interrupts or after enqueued.
 * The event cell shall be released or re-queued in this function.
 *
 * RETURN VALUE: n > 0  : the number of delivered events.
 *		 n == 0 : the event was not passed to any client.
 *		 n < 0  : error - event was not processed.
 */
int snd_seq_dispatch_event(struct snd_seq_event_cell *cell, int atomic, int hop)
{
	int result;

	if (snd_BUG_ON(!cell))
		return -EINVAL;

	struct snd_seq_client *client __free(snd_seq_client) =
		snd_seq_client_use_ptr(cell->event.source.client);
	if (client == NULL) {
		snd_seq_cell_free(cell); /* release this cell */
		return -EINVAL;
	}

	if (!snd_seq_ev_is_ump(&cell->event) &&
	    cell->event.type == SNDRV_SEQ_EVENT_NOTE) {
		/* NOTE event:
		 * the event cell is re-used as a NOTE-OFF event and
		 * enqueued again.
		 */
		struct snd_seq_event tmpev, *ev;

		/* reserve this event to enqueue note-off later */
		tmpev = cell->event;
		tmpev.type = SNDRV_SEQ_EVENT_NOTEON;
		result = snd_seq_deliver_event(client, &tmpev, atomic, hop);

		/*
		 * This was originally a note event.  We now re-use the
		 * cell for the note-off event.
		 */

		ev = &cell->event;
		ev->type = SNDRV_SEQ_EVENT_NOTEOFF;
		ev->flags |= SNDRV_SEQ_PRIORITY_HIGH;

		/* add the duration time */
		switch (ev->flags & SNDRV_SEQ_TIME_STAMP_MASK) {
		case SNDRV_SEQ_TIME_STAMP_TICK:
			cell->event.time.tick += ev->data.note.duration;
			break;
		case SNDRV_SEQ_TIME_STAMP_REAL:
			/* unit for duration is ms */
			ev->time.time.tv_nsec += 1000000 * (ev->data.note.duration % 1000);
			ev->time.time.tv_sec += ev->data.note.duration / 1000 +
						ev->time.time.tv_nsec / 1000000000;
			ev->time.time.tv_nsec %= 1000000000;
			break;
		}
		ev->data.note.velocity = ev->data.note.off_velocity;

		/* Now queue this cell as the note off event */
		if (snd_seq_enqueue_event(cell, atomic, hop) < 0)
			snd_seq_cell_free(cell); /* release this cell */

	} else {
		/* Normal events:
		 * event cell is freed after processing the event
		 */

		result = snd_seq_deliver_event(client, &cell->event, atomic, hop);
		snd_seq_cell_free(cell);
	}

	return result;
}


/* Allocate a cell from client pool and enqueue it to queue:
 * if pool is empty and blocking is TRUE, sleep until a new cell is
 * available.
 */
static int snd_seq_client_enqueue_event(struct snd_seq_client *client,
					struct snd_seq_event *event,
					struct file *file, int blocking,
					int atomic, int hop,
					struct mutex *mutexp)
{
	struct snd_seq_event_cell *cell;
	int err;

	/* special queue values - force direct passing */
	if (event->queue == SNDRV_SEQ_ADDRESS_SUBSCRIBERS) {
		event->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
		event->queue = SNDRV_SEQ_QUEUE_DIRECT;
	} else if (event->dest.client == SNDRV_SEQ_ADDRESS_SUBSCRIBERS) {
		/* check presence of source port */
		struct snd_seq_client_port *src_port __free(snd_seq_port) =
			snd_seq_port_use_ptr(client, event->source.port);
		if (!src_port)
			return -EINVAL;
	}

	/* direct event processing without enqueued */
	if (snd_seq_ev_is_direct(event)) {
		if (!snd_seq_ev_is_ump(event) &&
		    event->type == SNDRV_SEQ_EVENT_NOTE)
			return -EINVAL; /* this event must be enqueued! */
		return snd_seq_deliver_event(client, event, atomic, hop);
	}

	/* Not direct, normal queuing */
	if (snd_seq_queue_is_used(event->queue, client->number) <= 0)
		return -EINVAL;  /* invalid queue */
	if (! snd_seq_write_pool_allocated(client))
		return -ENXIO; /* queue is not allocated */

	/* allocate an event cell */
	err = snd_seq_event_dup(client->pool, event, &cell, !blocking || atomic,
				file, mutexp);
	if (err < 0)
		return err;

	/* we got a cell. enqueue it. */
	err = snd_seq_enqueue_event(cell, atomic, hop);
	if (err < 0) {
		snd_seq_cell_free(cell);
		return err;
	}

	return 0;
}


/*
 * check validity of event type and data length.
 * return non-zero if invalid.
 */
static int check_event_type_and_length(struct snd_seq_event *ev)
{
	switch (snd_seq_ev_length_type(ev)) {
	case SNDRV_SEQ_EVENT_LENGTH_FIXED:
		if (snd_seq_ev_is_variable_type(ev))
			return -EINVAL;
		break;
	case SNDRV_SEQ_EVENT_LENGTH_VARIABLE:
		if (! snd_seq_ev_is_variable_type(ev) ||
		    (ev->data.ext.len & ~SNDRV_SEQ_EXT_MASK) >= SNDRV_SEQ_MAX_EVENT_LEN)
			return -EINVAL;
		break;
	case SNDRV_SEQ_EVENT_LENGTH_VARUSR:
		if (! snd_seq_ev_is_direct(ev))
			return -EINVAL;
		break;
	}
	return 0;
}


/* handle write() */
/* possible error values:
 *	-ENXIO	invalid client or file open mode
 *	-ENOMEM	malloc failed
 *	-EFAULT	seg. fault during copy from user space
 *	-EINVAL	invalid event
 *	-EAGAIN	no space in output pool
 *	-EINTR	interrupts while sleep
 *	-EMLINK	too many hops
 *	others	depends on return value from driver callback
 */
static ssize_t snd_seq_write(struct file *file, const char __user *buf,
			     size_t count, loff_t *offset)
{
	struct snd_seq_client *client = file->private_data;
	int written = 0, len;
	int err, handled;
	union __snd_seq_event __event;
	struct snd_seq_event *ev = &__event.legacy;

	if (!(snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_OUTPUT))
		return -ENXIO;

	/* check client structures are in place */
	if (snd_BUG_ON(!client))
		return -ENXIO;
		
	if (!client->accept_output || client->pool == NULL)
		return -ENXIO;

 repeat:
	handled = 0;
	/* allocate the pool now if the pool is not allocated yet */ 
	mutex_lock(&client->ioctl_mutex);
	if (client->pool->size > 0 && !snd_seq_write_pool_allocated(client)) {
		err = snd_seq_pool_init(client->pool);
		if (err < 0)
			goto out;
	}

	/* only process whole events */
	err = -EINVAL;
	while (count >= sizeof(struct snd_seq_event)) {
		/* Read in the event header from the user */
		len = sizeof(struct snd_seq_event);
		if (copy_from_user(ev, buf, len)) {
			err = -EFAULT;
			break;
		}
		/* read in the rest bytes for UMP events */
		if (snd_seq_ev_is_ump(ev)) {
			if (count < sizeof(struct snd_seq_ump_event))
				break;
			if (copy_from_user((char *)ev + len, buf + len,
					   sizeof(struct snd_seq_ump_event) - len)) {
				err = -EFAULT;
				break;
			}
			len = sizeof(struct snd_seq_ump_event);
		}

		ev->source.client = client->number;	/* fill in client number */
		/* Check for extension data length */
		if (check_event_type_and_length(ev)) {
			err = -EINVAL;
			break;
		}

		if (!event_is_compatible(client, ev)) {
			err = -EINVAL;
			break;
		}

		/* check for special events */
		if (!snd_seq_ev_is_ump(ev)) {
			if (ev->type == SNDRV_SEQ_EVENT_NONE)
				goto __skip_event;
			else if (snd_seq_ev_is_reserved(ev)) {
				err = -EINVAL;
				break;
			}
		}

		if (snd_seq_ev_is_variable(ev)) {
			int extlen = ev->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
			if ((size_t)(extlen + len) > count) {
				/* back out, will get an error this time or next */
				err = -EINVAL;
				break;
			}
			/* set user space pointer */
			ev->data.ext.len = extlen | SNDRV_SEQ_EXT_USRPTR;
			ev->data.ext.ptr = (char __force *)buf + len;
			len += extlen; /* increment data length */
		} else {
#ifdef CONFIG_COMPAT
			if (client->convert32 && snd_seq_ev_is_varusr(ev))
				ev->data.ext.ptr =
					(void __force *)compat_ptr(ev->data.raw32.d[1]);
#endif
		}

		/* ok, enqueue it */
		err = snd_seq_client_enqueue_event(client, ev, file,
						   !(file->f_flags & O_NONBLOCK),
						   0, 0, &client->ioctl_mutex);
		if (err < 0)
			break;
		handled++;

	__skip_event:
		/* Update pointers and counts */
		count -= len;
		buf += len;
		written += len;

		/* let's have a coffee break if too many events are queued */
		if (++handled >= 200) {
			mutex_unlock(&client->ioctl_mutex);
			goto repeat;
		}
	}

 out:
	mutex_unlock(&client->ioctl_mutex);
	return written ? written : err;
}


/*
 * handle polling
 */
static __poll_t snd_seq_poll(struct file *file, poll_table * wait)
{
	struct snd_seq_client *client = file->private_data;
	__poll_t mask = 0;

	/* check client structures are in place */
	if (snd_BUG_ON(!client))
		return EPOLLERR;

	if ((snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_INPUT) &&
	    client->data.user.fifo) {

		/* check if data is available in the outqueue */
		if (snd_seq_fifo_poll_wait(client->data.user.fifo, file, wait))
			mask |= EPOLLIN | EPOLLRDNORM;
	}

	if (snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_OUTPUT) {

		/* check if data is available in the pool */
		if (snd_seq_pool_poll_wait(client->pool, file, wait))
			mask |= EPOLLOUT | EPOLLWRNORM;
	}

	return mask;
}


/*-----------------------------------------------------*/

static int snd_seq_ioctl_pversion(struct snd_seq_client *client, void *arg)
{
	int *pversion = arg;

	*pversion = SNDRV_SEQ_VERSION;
	return 0;
}

static int snd_seq_ioctl_user_pversion(struct snd_seq_client *client, void *arg)
{
	client->user_pversion = *(unsigned int *)arg;
	return 0;
}

static int snd_seq_ioctl_client_id(struct snd_seq_client *client, void *arg)
{
	int *client_id = arg;

	*client_id = client->number;
	return 0;
}

/* SYSTEM_INFO ioctl() */
static int snd_seq_ioctl_system_info(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_system_info *info = arg;

	memset(info, 0, sizeof(*info));
	/* fill the info fields */
	info->queues = SNDRV_SEQ_MAX_QUEUES;
	info->clients = SNDRV_SEQ_MAX_CLIENTS;
	info->ports = SNDRV_SEQ_MAX_PORTS;
	info->channels = 256;	/* fixed limit */
	info->cur_clients = client_usage.cur;
	info->cur_queues = snd_seq_queue_get_cur_queues();

	return 0;
}


/* RUNNING_MODE ioctl() */
static int snd_seq_ioctl_running_mode(struct snd_seq_client *client, void  *arg)
{
	struct snd_seq_running_info *info = arg;
	/* requested client number */
	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(info->client);

	if (cptr == NULL)
		return -ENOENT;		/* don't change !!! */

#ifdef SNDRV_BIG_ENDIAN
	if (!info->big_endian)
		return -EINVAL;
#else
	if (info->big_endian)
		return -EINVAL;
#endif
	if (info->cpu_mode > sizeof(long))
		return -EINVAL;
	cptr->convert32 = (info->cpu_mode < sizeof(long));
	return 0;
}

/* CLIENT_INFO ioctl() */
static void get_client_info(struct snd_seq_client *cptr,
			    struct snd_seq_client_info *info)
{
	info->client = cptr->number;

	/* fill the info fields */
	info->type = cptr->type;
	strscpy(info->name, cptr->name);
	info->filter = cptr->filter;
	info->event_lost = cptr->event_lost;
	memcpy(info->event_filter, cptr->event_filter, 32);
	info->group_filter = cptr->group_filter;
	info->num_ports = cptr->num_ports;

	if (cptr->type == USER_CLIENT)
		info->pid = pid_vnr(cptr->data.user.owner);
	else
		info->pid = -1;

	if (cptr->type == KERNEL_CLIENT)
		info->card = cptr->data.kernel.card ? cptr->data.kernel.card->number : -1;
	else
		info->card = -1;

	info->midi_version = cptr->midi_version;
	memset(info->reserved, 0, sizeof(info->reserved));
}

static int snd_seq_ioctl_get_client_info(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_client_info *client_info = arg;
	/* requested client number */
	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(client_info->client);

	if (cptr == NULL)
		return -ENOENT;		/* don't change !!! */

	get_client_info(cptr, client_info);
	return 0;
}


/* CLIENT_INFO ioctl() */
static int snd_seq_ioctl_set_client_info(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_client_info *client_info = arg;

	/* it is not allowed to set the info fields for an another client */
	if (client->number != client_info->client)
		return -EPERM;
	/* also client type must be set now */
	if (client->type != client_info->type)
		return -EINVAL;

	if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3)) {
		/* check validity of midi_version field */
		if (client_info->midi_version > SNDRV_SEQ_CLIENT_UMP_MIDI_2_0)
			return -EINVAL;

		/* check if UMP is supported in kernel */
		if (!IS_ENABLED(CONFIG_SND_SEQ_UMP) &&
		    client_info->midi_version > 0)
			return -EINVAL;
	}

	/* fill the info fields */
	if (client_info->name[0])
		strscpy(client->name, client_info->name, sizeof(client->name));

	client->filter = client_info->filter;
	client->event_lost = client_info->event_lost;
	if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3))
		client->midi_version = client_info->midi_version;
	memcpy(client->event_filter, client_info->event_filter, 32);
	client->group_filter = client_info->group_filter & SND_SEQ_GROUP_FILTER_MASK;

	/* notify the change */
	snd_seq_system_client_ev_client_change(client->number);

	return 0;
}


/* 
 * CREATE PORT ioctl() 
 */
static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_port_info *info = arg;
	struct snd_seq_client_port *port;
	struct snd_seq_port_callback *callback;
	int port_idx, err;

	/* it is not allowed to create the port for an another client */
	if (info->addr.client != client->number)
		return -EPERM;
	if (client->type == USER_CLIENT && info->kernel)
		return -EINVAL;
	if ((info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT) &&
	    client->ump_endpoint_port >= 0)
		return -EBUSY;

	if (info->flags & SNDRV_SEQ_PORT_FLG_GIVEN_PORT)
		port_idx = info->addr.port;
	else
		port_idx = -1;
	if (port_idx >= SNDRV_SEQ_ADDRESS_UNKNOWN)
		return -EINVAL;
	err = snd_seq_create_port(client, port_idx, &port);
	if (err < 0)
		return err;

	if (client->type == KERNEL_CLIENT) {
		callback = info->kernel;
		if (callback) {
			if (callback->owner)
				port->owner = callback->owner;
			port->private_data = callback->private_data;
			port->private_free = callback->private_free;
			port->event_input = callback->event_input;
			port->c_src.open = callback->subscribe;
			port->c_src.close = callback->unsubscribe;
			port->c_dest.open = callback->use;
			port->c_dest.close = callback->unuse;
		}
	}

	info->addr = port->addr;

	snd_seq_set_port_info(port, info);
	if (info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT)
		client->ump_endpoint_port = port->addr.port;
	snd_seq_system_client_ev_port_start(port->addr.client, port->addr.port);
	snd_seq_port_unlock(port);

	return 0;
}

/* 
 * DELETE PORT ioctl() 
 */
static int snd_seq_ioctl_delete_port(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_port_info *info = arg;
	int err;

	/* it is not allowed to remove the port for an another client */
	if (info->addr.client != client->number)
		return -EPERM;

	err = snd_seq_delete_port(client, info->addr.port);
	if (err >= 0) {
		if (client->ump_endpoint_port == info->addr.port)
			client->ump_endpoint_port = -1;
		snd_seq_system_client_ev_port_exit(client->number, info->addr.port);
	}
	return err;
}


/* 
 * GET_PORT_INFO ioctl() (on any client) 
 */
static int snd_seq_ioctl_get_port_info(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_port_info *info = arg;

	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(info->addr.client);
	if (cptr == NULL)
		return -ENXIO;

	struct snd_seq_client_port *port __free(snd_seq_port) =
		snd_seq_port_use_ptr(cptr, info->addr.port);
	if (port == NULL)
		return -ENOENT;			/* don't change */

	/* get port info */
	snd_seq_get_port_info(port, info);
	return 0;
}


/* 
 * SET_PORT_INFO ioctl() (only ports on this/own client) 
 */
static int snd_seq_ioctl_set_port_info(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_port_info *info = arg;

	if (info->addr.client != client->number) /* only set our own ports ! */
		return -EPERM;

	struct snd_seq_client_port *port __free(snd_seq_port) =
		snd_seq_port_use_ptr(client, info->addr.port);
	if (port) {
		snd_seq_set_port_info(port, info);
		/* notify the change */
		snd_seq_system_client_ev_port_change(info->addr.client,
						     info->addr.port);
	}
	return 0;
}


/*
 * port subscription (connection)
 */
#define PERM_RD		(SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ)
#define PERM_WR		(SNDRV_SEQ_PORT_CAP_WRITE|SNDRV_SEQ_PORT_CAP_SUBS_WRITE)

static int check_subscription_permission(struct snd_seq_client *client,
					 struct snd_seq_client_port *sport,
					 struct snd_seq_client_port *dport,
					 struct snd_seq_port_subscribe *subs)
{
	if (client->number != subs->sender.client &&
	    client->number != subs->dest.client) {
		/* connection by third client - check export permission */
		if (check_port_perm(sport, SNDRV_SEQ_PORT_CAP_NO_EXPORT))
			return -EPERM;
		if (check_port_perm(dport, SNDRV_SEQ_PORT_CAP_NO_EXPORT))
			return -EPERM;
	}

	/* check read permission */
	/* if sender or receiver is the subscribing client itself,
	 * no permission check is necessary
	 */
	if (client->number != subs->sender.client) {
		if (! check_port_perm(sport, PERM_RD))
			return -EPERM;
	}
	/* check write permission */
	if (client->number != subs->dest.client) {
		if (! check_port_perm(dport, PERM_WR))
			return -EPERM;
	}
	return 0;
}

/*
 * send an subscription notify event to user client:
 * client must be user client.
 */
int snd_seq_client_notify_subscription(int client, int port,
				       struct snd_seq_port_subscribe *info,
				       int evtype)
{
	struct snd_seq_event event;

	memset(&event, 0, sizeof(event));
	event.type = evtype;
	event.data.connect.dest = info->dest;
	event.data.connect.sender = info->sender;

	return snd_seq_system_notify(client, port, &event, false);  /* non-atomic */
}


/* 
 * add to port's subscription list IOCTL interface 
 */
static int snd_seq_ioctl_subscribe_port(struct snd_seq_client *client,
					void *arg)
{
	struct snd_seq_port_subscribe *subs = arg;
	int result;

	struct snd_seq_client *receiver __free(snd_seq_client) =
		client_load_and_use_ptr(subs->dest.client);
	if (!receiver)
		return -EINVAL;
	struct snd_seq_client *sender __free(snd_seq_client) =
		client_load_and_use_ptr(subs->sender.client);
	if (!sender)
		return -EINVAL;
	struct snd_seq_client_port *sport __free(snd_seq_port) =
		snd_seq_port_use_ptr(sender, subs->sender.port);
	if (!sport)
		return -EINVAL;
	struct snd_seq_client_port *dport __free(snd_seq_port) =
		snd_seq_port_use_ptr(receiver, subs->dest.port);
	if (!dport)
		return -EINVAL;

	result = check_subscription_permission(client, sport, dport, subs);
	if (result < 0)
		return result;

	/* connect them */
	result = snd_seq_port_connect(client, sender, sport, receiver, dport, subs);
	if (! result) /* broadcast announce */
		snd_seq_client_notify_subscription(SNDRV_SEQ_ADDRESS_SUBSCRIBERS, 0,
						   subs, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
	return result;
}


/* 
 * remove from port's subscription list 
 */
static int snd_seq_ioctl_unsubscribe_port(struct snd_seq_client *client,
					  void *arg)
{
	struct snd_seq_port_subscribe *subs = arg;
	int result;

	struct snd_seq_client *receiver __free(snd_seq_client) =
		snd_seq_client_use_ptr(subs->dest.client);
	if (!receiver)
		return -ENXIO;
	struct snd_seq_client *sender __free(snd_seq_client) =
		snd_seq_client_use_ptr(subs->sender.client);
	if (!sender)
		return -ENXIO;
	struct snd_seq_client_port *sport __free(snd_seq_port) =
		snd_seq_port_use_ptr(sender, subs->sender.port);
	if (!sport)
		return -ENXIO;
	struct snd_seq_client_port *dport __free(snd_seq_port) =
		snd_seq_port_use_ptr(receiver, subs->dest.port);
	if (!dport)
		return -ENXIO;

	result = check_subscription_permission(client, sport, dport, subs);
	if (result < 0)
		return result;

	result = snd_seq_port_disconnect(client, sender, sport, receiver, dport, subs);
	if (! result) /* broadcast announce */
		snd_seq_client_notify_subscription(SNDRV_SEQ_ADDRESS_SUBSCRIBERS, 0,
						   subs, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
	return result;
}


/* CREATE_QUEUE ioctl() */
static int snd_seq_ioctl_create_queue(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_queue_info *info = arg;
	struct snd_seq_queue *q __free(snd_seq_queue) =
		snd_seq_queue_alloc(client->number, info->locked, info->flags);

	if (IS_ERR(q))
		return PTR_ERR(q);

	info->queue = q->queue;
	info->locked = q->locked;
	info->owner = q->owner;

	/* set queue name */
	if (!info->name[0])
		snprintf(info->name, sizeof(info->name), "Queue-%d", q->queue);
	strscpy(q->name, info->name, sizeof(q->name));

	return 0;
}

/* DELETE_QUEUE ioctl() */
static int snd_seq_ioctl_delete_queue(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_queue_info *info = arg;

	return snd_seq_queue_delete(client->number, info->queue);
}

/* GET_QUEUE_INFO ioctl() */
static int snd_seq_ioctl_get_queue_info(struct snd_seq_client *client,
					void *arg)
{
	struct snd_seq_queue_info *info = arg;
	struct snd_seq_queue *q __free(snd_seq_queue) =
		queueptr(info->queue);

	if (q == NULL)
		return -EINVAL;

	memset(info, 0, sizeof(*info));
	info->queue = q->queue;
	info->owner = q->owner;
	info->locked = q->locked;
	strscpy(info->name, q->name, sizeof(info->name));

	return 0;
}

/* SET_QUEUE_INFO ioctl() */
static int snd_seq_ioctl_set_queue_info(struct snd_seq_client *client,
					void *arg)
{
	struct snd_seq_queue_info *info = arg;

	if (info->owner != client->number)
		return -EINVAL;

	/* change owner/locked permission */
	if (snd_seq_queue_check_access(info->queue, client->number)) {
		if (snd_seq_queue_set_owner(info->queue, client->number, info->locked) < 0)
			return -EPERM;
		if (info->locked)
			snd_seq_queue_use(info->queue, client->number, 1);
	} else {
		return -EPERM;
	}	

	struct snd_seq_queue *q __free(snd_seq_queue) =
		queueptr(info->queue);
	if (! q)
		return -EINVAL;
	if (q->owner != client->number)
		return -EPERM;
	strscpy(q->name, info->name, sizeof(q->name));

	return 0;
}

/* GET_NAMED_QUEUE ioctl() */
static int snd_seq_ioctl_get_named_queue(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_queue_info *info = arg;
	struct snd_seq_queue *q __free(snd_seq_queue) =
		snd_seq_queue_find_name(info->name);

	if (q == NULL)
		return -EINVAL;
	info->queue = q->queue;
	info->owner = q->owner;
	info->locked = q->locked;

	return 0;
}

/* GET_QUEUE_STATUS ioctl() */
static int snd_seq_ioctl_get_queue_status(struct snd_seq_client *client,
					  void *arg)
{
	struct snd_seq_queue_status *status = arg;
	struct snd_seq_timer *tmr;
	struct snd_seq_queue *queue __free(snd_seq_queue) =
		queueptr(status->queue);

	if (queue == NULL)
		return -EINVAL;
	memset(status, 0, sizeof(*status));
	status->queue = queue->queue;
	
	tmr = queue->timer;
	status->events = queue->tickq->cells + queue->timeq->cells;

	status->time = snd_seq_timer_get_cur_time(tmr, true);
	status->tick = snd_seq_timer_get_cur_tick(tmr);

	status->running = tmr->running;

	status->flags = queue->flags;

	return 0;
}


/* GET_QUEUE_TEMPO ioctl() */
static int snd_seq_ioctl_get_queue_tempo(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_queue_tempo *tempo = arg;
	struct snd_seq_timer *tmr;
	struct snd_seq_queue *queue __free(snd_seq_queue) =
		queueptr(tempo->queue);

	if (queue == NULL)
		return -EINVAL;
	memset(tempo, 0, sizeof(*tempo));
	tempo->queue = queue->queue;
	
	tmr = queue->timer;

	tempo->tempo = tmr->tempo;
	tempo->ppq = tmr->ppq;
	tempo->skew_value = tmr->skew;
	tempo->skew_base = tmr->skew_base;
	if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 4))
		tempo->tempo_base = tmr->tempo_base;

	return 0;
}


/* SET_QUEUE_TEMPO ioctl() */
int snd_seq_set_queue_tempo(int client, struct snd_seq_queue_tempo *tempo)
{
	if (!snd_seq_queue_check_access(tempo->queue, client))
		return -EPERM;
	return snd_seq_queue_timer_set_tempo(tempo->queue, client, tempo);
}
EXPORT_SYMBOL(snd_seq_set_queue_tempo);

static int snd_seq_ioctl_set_queue_tempo(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_queue_tempo *tempo = arg;
	int result;

	if (client->user_pversion < SNDRV_PROTOCOL_VERSION(1, 0, 4))
		tempo->tempo_base = 0;
	result = snd_seq_set_queue_tempo(client->number, tempo);
	return result < 0 ? result : 0;
}


/* GET_QUEUE_TIMER ioctl() */
static int snd_seq_ioctl_get_queue_timer(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_queue_timer *timer = arg;
	struct snd_seq_timer *tmr;
	struct snd_seq_queue *queue __free(snd_seq_queue) =
		queueptr(timer->queue);

	if (queue == NULL)
		return -EINVAL;

	guard(mutex)(&queue->timer_mutex);
	tmr = queue->timer;
	memset(timer, 0, sizeof(*timer));
	timer->queue = queue->queue;

	timer->type = tmr->type;
	if (tmr->type == SNDRV_SEQ_TIMER_ALSA) {
		timer->u.alsa.id = tmr->alsa_id;
		timer->u.alsa.resolution = tmr->preferred_resolution;
	}
	
	return 0;
}


/* SET_QUEUE_TIMER ioctl() */
static int snd_seq_ioctl_set_queue_timer(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_queue_timer *timer = arg;
	int result = 0;

	if (timer->type != SNDRV_SEQ_TIMER_ALSA)
		return -EINVAL;

	if (snd_seq_queue_check_access(timer->queue, client->number)) {
		struct snd_seq_timer *tmr;
		struct snd_seq_queue *q __free(snd_seq_queue) =
			queueptr(timer->queue);

		if (q == NULL)
			return -ENXIO;
		guard(mutex)(&q->timer_mutex);
		tmr = q->timer;
		snd_seq_queue_timer_close(timer->queue);
		tmr->type = timer->type;
		if (tmr->type == SNDRV_SEQ_TIMER_ALSA) {
			tmr->alsa_id = timer->u.alsa.id;
			tmr->preferred_resolution = timer->u.alsa.resolution;
		}
		result = snd_seq_queue_timer_open(timer->queue);
	} else {
		return -EPERM;
	}	

	return result;
}


/* GET_QUEUE_CLIENT ioctl() */
static int snd_seq_ioctl_get_queue_client(struct snd_seq_client *client,
					  void *arg)
{
	struct snd_seq_queue_client *info = arg;
	int used;

	used = snd_seq_queue_is_used(info->queue, client->number);
	if (used < 0)
		return -EINVAL;
	info->used = used;
	info->client = client->number;

	return 0;
}


/* SET_QUEUE_CLIENT ioctl() */
static int snd_seq_ioctl_set_queue_client(struct snd_seq_client *client,
					  void *arg)
{
	struct snd_seq_queue_client *info = arg;
	int err;

	if (info->used >= 0) {
		err = snd_seq_queue_use(info->queue, client->number, info->used);
		if (err < 0)
			return err;
	}

	return snd_seq_ioctl_get_queue_client(client, arg);
}


/* GET_CLIENT_POOL ioctl() */
static int snd_seq_ioctl_get_client_pool(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_client_pool *info = arg;
	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(info->client);

	if (cptr == NULL)
		return -ENOENT;
	memset(info, 0, sizeof(*info));
	info->client = cptr->number;
	info->output_pool = cptr->pool->size;
	info->output_room = cptr->pool->room;
	info->output_free = info->output_pool;
	info->output_free = snd_seq_unused_cells(cptr->pool);
	if (cptr->type == USER_CLIENT) {
		info->input_pool = cptr->data.user.fifo_pool_size;
		info->input_free = info->input_pool;
		info->input_free = snd_seq_fifo_unused_cells(cptr->data.user.fifo);
	} else {
		info->input_pool = 0;
		info->input_free = 0;
	}
	
	return 0;
}

/* SET_CLIENT_POOL ioctl() */
static int snd_seq_ioctl_set_client_pool(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_client_pool *info = arg;
	int rc;

	if (client->number != info->client)
		return -EINVAL; /* can't change other clients */

	if (info->output_pool >= 1 && info->output_pool <= SNDRV_SEQ_MAX_EVENTS &&
	    (! snd_seq_write_pool_allocated(client) ||
	     info->output_pool != client->pool->size)) {
		if (snd_seq_write_pool_allocated(client)) {
			/* is the pool in use? */
			if (atomic_read(&client->pool->counter))
				return -EBUSY;
			/* remove all existing cells */
			snd_seq_pool_mark_closing(client->pool);
			snd_seq_pool_done(client->pool);
		}
		client->pool->size = info->output_pool;
		rc = snd_seq_pool_init(client->pool);
		if (rc < 0)
			return rc;
	}
	if (client->type == USER_CLIENT && client->data.user.fifo != NULL &&
	    info->input_pool >= 1 &&
	    info->input_pool <= SNDRV_SEQ_MAX_CLIENT_EVENTS &&
	    info->input_pool != client->data.user.fifo_pool_size) {
		/* change pool size */
		rc = snd_seq_fifo_resize(client->data.user.fifo, info->input_pool);
		if (rc < 0)
			return rc;
		client->data.user.fifo_pool_size = info->input_pool;
	}
	if (info->output_room >= 1 &&
	    info->output_room <= client->pool->size) {
		client->pool->room  = info->output_room;
	}

	return snd_seq_ioctl_get_client_pool(client, arg);
}


/* REMOVE_EVENTS ioctl() */
static int snd_seq_ioctl_remove_events(struct snd_seq_client *client,
				       void *arg)
{
	struct snd_seq_remove_events *info = arg;

	/*
	 * Input mostly not implemented XXX.
	 */
	if (info->remove_mode & SNDRV_SEQ_REMOVE_INPUT) {
		/*
		 * No restrictions so for a user client we can clear
		 * the whole fifo
		 */
		if (client->type == USER_CLIENT && client->data.user.fifo)
			snd_seq_fifo_clear(client->data.user.fifo);
	}

	if (info->remove_mode & SNDRV_SEQ_REMOVE_OUTPUT)
		snd_seq_queue_remove_cells(client->number, info);

	return 0;
}


/*
 * get subscription info
 */
static int snd_seq_ioctl_get_subscription(struct snd_seq_client *client,
					  void *arg)
{
	struct snd_seq_port_subscribe *subs = arg;

	struct snd_seq_client *sender __free(snd_seq_client) =
		client_load_and_use_ptr(subs->sender.client);
	if (!sender)
		return -EINVAL;
	struct snd_seq_client_port *sport __free(snd_seq_port) =
		snd_seq_port_use_ptr(sender, subs->sender.port);
	if (!sport)
		return -EINVAL;
	return snd_seq_port_get_subscription(&sport->c_src, &subs->dest, subs);
}


/*
 * get subscription info - check only its presence
 */
static int snd_seq_ioctl_query_subs(struct snd_seq_client *client, void *arg)
{
	struct snd_seq_query_subs *subs = arg;
	struct snd_seq_port_subs_info *group;
	struct list_head *p;
	int i;

	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(subs->root.client);
	if (!cptr)
		return -ENXIO;
	struct snd_seq_client_port *port __free(snd_seq_port) =
		snd_seq_port_use_ptr(cptr, subs->root.port);
	if (!port)
		return -ENXIO;

	switch (subs->type) {
	case SNDRV_SEQ_QUERY_SUBS_READ:
		group = &port->c_src;
		break;
	case SNDRV_SEQ_QUERY_SUBS_WRITE:
		group = &port->c_dest;
		break;
	default:
		return -ENXIO;
	}

	guard(rwsem_read)(&group->list_mutex);
	/* search for the subscriber */
	subs->num_subs = group->count;
	i = 0;
	list_for_each(p, &group->list_head) {
		if (i++ == subs->index) {
			/* found! */
			struct snd_seq_subscribers *s;
			if (subs->type == SNDRV_SEQ_QUERY_SUBS_READ) {
				s = list_entry(p, struct snd_seq_subscribers, src_list);
				subs->addr = s->info.dest;
			} else {
				s = list_entry(p, struct snd_seq_subscribers, dest_list);
				subs->addr = s->info.sender;
			}
			subs->flags = s->info.flags;
			subs->queue = s->info.queue;
			return 0;
		}
	}

	return -ENOENT;
}


/*
 * query next client
 */
static int snd_seq_ioctl_query_next_client(struct snd_seq_client *client,
					   void *arg)
{
	struct snd_seq_client_info *info = arg;

	/* search for next client */
	if (info->client < INT_MAX)
		info->client++;
	if (info->client < 0)
		info->client = 0;
	for (; info->client < SNDRV_SEQ_MAX_CLIENTS; info->client++) {
		struct snd_seq_client *cptr __free(snd_seq_client) =
			client_load_and_use_ptr(info->client);
		if (cptr) {
			get_client_info(cptr, info);
			return 0; /* found */
		}
	}
	return -ENOENT;
}

/* 
 * query next port
 */
static int snd_seq_ioctl_query_next_port(struct snd_seq_client *client,
					 void *arg)
{
	struct snd_seq_port_info *info = arg;

	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(info->addr.client);
	if (cptr == NULL)
		return -ENXIO;

	/* search for next port */
	info->addr.port++;
	struct snd_seq_client_port *port __free(snd_seq_port) =
		snd_seq_port_query_nearest(cptr, info);
	if (port == NULL)
		return -ENOENT;

	/* get port info */
	info->addr = port->addr;
	snd_seq_get_port_info(port, info);

	return 0;
}

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
#define NUM_UMP_INFOS (SNDRV_UMP_MAX_BLOCKS + 1)

static void free_ump_info(struct snd_seq_client *client)
{
	int i;

	if (!client->ump_info)
		return;
	for (i = 0; i < NUM_UMP_INFOS; i++)
		kfree(client->ump_info[i]);
	kfree(client->ump_info);
	client->ump_info = NULL;
}

static void terminate_ump_info_strings(void *p, int type)
{
	if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT) {
		struct snd_ump_endpoint_info *ep = p;
		ep->name[sizeof(ep->name) - 1] = 0;
	} else {
		struct snd_ump_block_info *bp = p;
		bp->name[sizeof(bp->name) - 1] = 0;
	}
}

#ifdef CONFIG_SND_PROC_FS
static void dump_ump_info(struct snd_info_buffer *buffer,
			  struct snd_seq_client *client)
{
	struct snd_ump_endpoint_info *ep;
	struct snd_ump_block_info *bp;
	int i;

	if (!client->ump_info)
		return;
	ep = client->ump_info[SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT];
	if (ep && *ep->name)
		snd_iprintf(buffer, "  UMP Endpoint: \"%s\"\n", ep->name);
	for (i = 0; i < SNDRV_UMP_MAX_BLOCKS; i++) {
		bp = client->ump_info[i + 1];
		if (bp && *bp->name) {
			snd_iprintf(buffer, "  UMP Block %d: \"%s\" [%s]\n",
				    i, bp->name,
				    bp->active ? "Active" : "Inactive");
			snd_iprintf(buffer, "    Groups: %d-%d\n",
				    bp->first_group + 1,
				    bp->first_group + bp->num_groups);
		}
	}
}
#endif

/* UMP-specific ioctls -- called directly without data copy */
static int snd_seq_ioctl_client_ump_info(struct snd_seq_client *caller,
					 unsigned int cmd,
					 unsigned long arg)
{
	struct snd_seq_client_ump_info __user *argp =
		(struct snd_seq_client_ump_info __user *)arg;
	int client, type, err = 0;
	size_t size;
	void *p;

	if (get_user(client, &argp->client) || get_user(type, &argp->type))
		return -EFAULT;
	if (cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO &&
	    caller->number != client)
		return -EPERM;
	if (type < 0 || type >= NUM_UMP_INFOS)
		return -EINVAL;
	if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT)
		size = sizeof(struct snd_ump_endpoint_info);
	else
		size = sizeof(struct snd_ump_block_info);

	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(client);
	if (!cptr)
		return -ENOENT;

	scoped_guard(mutex, &cptr->ioctl_mutex) {
		if (!cptr->midi_version) {
			err = -EBADFD;
			break;
		}

		if (cmd == SNDRV_SEQ_IOCTL_GET_CLIENT_UMP_INFO) {
			if (!cptr->ump_info)
				p = NULL;
			else
				p = cptr->ump_info[type];
			if (!p) {
				err = -ENODEV;
				break;
			}
			if (copy_to_user(argp->info, p, size)) {
				err = -EFAULT;
				break;
			}
		} else {
			if (cptr->type != USER_CLIENT) {
				err = -EBADFD;
				break;
			}
			if (!cptr->ump_info) {
				cptr->ump_info = kcalloc(NUM_UMP_INFOS,
							 sizeof(void *), GFP_KERNEL);
				if (!cptr->ump_info) {
					err = -ENOMEM;
					break;
				}
			}
			p = memdup_user(argp->info, size);
			if (IS_ERR(p)) {
				err = PTR_ERR(p);
				break;
			}
			kfree(cptr->ump_info[type]);
			terminate_ump_info_strings(p, type);
			cptr->ump_info[type] = p;
		}

	}
	if (!err && cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO) {
		if (type == SNDRV_SEQ_CLIENT_UMP_INFO_ENDPOINT)
			snd_seq_system_ump_notify(client, 0,
						  SNDRV_SEQ_EVENT_UMP_EP_CHANGE,
						  false);
		else
			snd_seq_system_ump_notify(client, type - 1,
						  SNDRV_SEQ_EVENT_UMP_BLOCK_CHANGE,
						  false);
	}
	return err;
}
#endif

/* -------------------------------------------------------- */

static const struct ioctl_handler {
	unsigned int cmd;
	int (*func)(struct snd_seq_client *client, void *arg);
} ioctl_handlers[] = {
	{ SNDRV_SEQ_IOCTL_PVERSION, snd_seq_ioctl_pversion },
	{ SNDRV_SEQ_IOCTL_USER_PVERSION, snd_seq_ioctl_user_pversion },
	{ SNDRV_SEQ_IOCTL_CLIENT_ID, snd_seq_ioctl_client_id },
	{ SNDRV_SEQ_IOCTL_SYSTEM_INFO, snd_seq_ioctl_system_info },
	{ SNDRV_SEQ_IOCTL_RUNNING_MODE, snd_seq_ioctl_running_mode },
	{ SNDRV_SEQ_IOCTL_GET_CLIENT_INFO, snd_seq_ioctl_get_client_info },
	{ SNDRV_SEQ_IOCTL_SET_CLIENT_INFO, snd_seq_ioctl_set_client_info },
	{ SNDRV_SEQ_IOCTL_CREATE_PORT, snd_seq_ioctl_create_port },
	{ SNDRV_SEQ_IOCTL_DELETE_PORT, snd_seq_ioctl_delete_port },
	{ SNDRV_SEQ_IOCTL_GET_PORT_INFO, snd_seq_ioctl_get_port_info },
	{ SNDRV_SEQ_IOCTL_SET_PORT_INFO, snd_seq_ioctl_set_port_info },
	{ SNDRV_SEQ_IOCTL_SUBSCRIBE_PORT, snd_seq_ioctl_subscribe_port },
	{ SNDRV_SEQ_IOCTL_UNSUBSCRIBE_PORT, snd_seq_ioctl_unsubscribe_port },
	{ SNDRV_SEQ_IOCTL_CREATE_QUEUE, snd_seq_ioctl_create_queue },
	{ SNDRV_SEQ_IOCTL_DELETE_QUEUE, snd_seq_ioctl_delete_queue },
	{ SNDRV_SEQ_IOCTL_GET_QUEUE_INFO, snd_seq_ioctl_get_queue_info },
	{ SNDRV_SEQ_IOCTL_SET_QUEUE_INFO, snd_seq_ioctl_set_queue_info },
	{ SNDRV_SEQ_IOCTL_GET_NAMED_QUEUE, snd_seq_ioctl_get_named_queue },
	{ SNDRV_SEQ_IOCTL_GET_QUEUE_STATUS, snd_seq_ioctl_get_queue_status },
	{ SNDRV_SEQ_IOCTL_GET_QUEUE_TEMPO, snd_seq_ioctl_get_queue_tempo },
	{ SNDRV_SEQ_IOCTL_SET_QUEUE_TEMPO, snd_seq_ioctl_set_queue_tempo },
	{ SNDRV_SEQ_IOCTL_GET_QUEUE_TIMER, snd_seq_ioctl_get_queue_timer },
	{ SNDRV_SEQ_IOCTL_SET_QUEUE_TIMER, snd_seq_ioctl_set_queue_timer },
	{ SNDRV_SEQ_IOCTL_GET_QUEUE_CLIENT, snd_seq_ioctl_get_queue_client },
	{ SNDRV_SEQ_IOCTL_SET_QUEUE_CLIENT, snd_seq_ioctl_set_queue_client },
	{ SNDRV_SEQ_IOCTL_GET_CLIENT_POOL, snd_seq_ioctl_get_client_pool },
	{ SNDRV_SEQ_IOCTL_SET_CLIENT_POOL, snd_seq_ioctl_set_client_pool },
	{ SNDRV_SEQ_IOCTL_GET_SUBSCRIPTION, snd_seq_ioctl_get_subscription },
	{ SNDRV_SEQ_IOCTL_QUERY_NEXT_CLIENT, snd_seq_ioctl_query_next_client },
	{ SNDRV_SEQ_IOCTL_QUERY_NEXT_PORT, snd_seq_ioctl_query_next_port },
	{ SNDRV_SEQ_IOCTL_REMOVE_EVENTS, snd_seq_ioctl_remove_events },
	{ SNDRV_SEQ_IOCTL_QUERY_SUBS, snd_seq_ioctl_query_subs },
	{ 0, NULL },
};

static long snd_seq_ioctl(struct file *file, unsigned int cmd,
			  unsigned long arg)
{
	struct snd_seq_client *client = file->private_data;
	/* To use kernel stack for ioctl data. */
	union {
		int pversion;
		int client_id;
		struct snd_seq_system_info	system_info;
		struct snd_seq_running_info	running_info;
		struct snd_seq_client_info	client_info;
		struct snd_seq_port_info	port_info;
		struct snd_seq_port_subscribe	port_subscribe;
		struct snd_seq_queue_info	queue_info;
		struct snd_seq_queue_status	queue_status;
		struct snd_seq_queue_tempo	tempo;
		struct snd_seq_queue_timer	queue_timer;
		struct snd_seq_queue_client	queue_client;
		struct snd_seq_client_pool	client_pool;
		struct snd_seq_remove_events	remove_events;
		struct snd_seq_query_subs	query_subs;
	} buf;
	const struct ioctl_handler *handler;
	unsigned long size;
	int err;

	if (snd_BUG_ON(!client))
		return -ENXIO;

#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
	/* exception - handling large data */
	switch (cmd) {
	case SNDRV_SEQ_IOCTL_GET_CLIENT_UMP_INFO:
	case SNDRV_SEQ_IOCTL_SET_CLIENT_UMP_INFO:
		return snd_seq_ioctl_client_ump_info(client, cmd, arg);
	}
#endif

	for (handler = ioctl_handlers; handler->cmd > 0; ++handler) {
		if (handler->cmd == cmd)
			break;
	}
	if (handler->cmd == 0)
		return -ENOTTY;

	memset(&buf, 0, sizeof(buf));

	/*
	 * All of ioctl commands for ALSA sequencer get an argument of size
	 * within 13 bits. We can safely pick up the size from the command.
	 */
	size = _IOC_SIZE(handler->cmd);
	if (handler->cmd & IOC_IN) {
		if (copy_from_user(&buf, (const void __user *)arg, size))
			return -EFAULT;
	}

	scoped_guard(mutex, &client->ioctl_mutex) {
		err = handler->func(client, &buf);
	}
	if (err >= 0) {
		/* Some commands includes a bug in 'dir' field. */
		if (handler->cmd == SNDRV_SEQ_IOCTL_SET_QUEUE_CLIENT ||
		    handler->cmd == SNDRV_SEQ_IOCTL_SET_CLIENT_POOL ||
		    (handler->cmd & IOC_OUT))
			if (copy_to_user((void __user *)arg, &buf, size))
				return -EFAULT;
	}

	return err;
}

#ifdef CONFIG_COMPAT
#include "seq_compat.c"
#else
#define snd_seq_ioctl_compat	NULL
#endif

/* -------------------------------------------------------- */


/* exported to kernel modules */
int snd_seq_create_kernel_client(struct snd_card *card, int client_index,
				 const char *name_fmt, ...)
{
	struct snd_seq_client *client;
	va_list args;

	if (snd_BUG_ON(in_interrupt()))
		return -EBUSY;

	if (card && client_index >= SNDRV_SEQ_CLIENTS_PER_CARD)
		return -EINVAL;
	if (card == NULL && client_index >= SNDRV_SEQ_GLOBAL_CLIENTS)
		return -EINVAL;

	scoped_guard(mutex, &register_mutex) {

		if (card) {
			client_index += SNDRV_SEQ_GLOBAL_CLIENTS
				+ card->number * SNDRV_SEQ_CLIENTS_PER_CARD;
			if (client_index >= SNDRV_SEQ_DYNAMIC_CLIENTS_BEGIN)
				client_index = -1;
		}

		/* empty write queue as default */
		client = seq_create_client1(client_index, 0);
		if (client == NULL)
			return -EBUSY;	/* failure code */
		usage_alloc(&client_usage, 1);

		client->accept_input = 1;
		client->accept_output = 1;
		client->data.kernel.card = card;
		client->user_pversion = SNDRV_SEQ_VERSION;
		
		va_start(args, name_fmt);
		vsnprintf(client->name, sizeof(client->name), name_fmt, args);
		va_end(args);

		client->type = KERNEL_CLIENT;
	}

	/* make others aware this new client */
	snd_seq_system_client_ev_client_start(client->number);
	
	/* return client number to caller */
	return client->number;
}
EXPORT_SYMBOL(snd_seq_create_kernel_client);

/* exported to kernel modules */
int snd_seq_delete_kernel_client(int client)
{
	struct snd_seq_client *ptr;

	if (snd_BUG_ON(in_interrupt()))
		return -EBUSY;

	ptr = clientptr(client);
	if (ptr == NULL)
		return -EINVAL;

	seq_free_client(ptr);
	kfree(ptr);
	return 0;
}
EXPORT_SYMBOL(snd_seq_delete_kernel_client);

/*
 * exported, called by kernel clients to enqueue events (w/o blocking)
 *
 * RETURN VALUE: zero if succeed, negative if error
 */
int snd_seq_kernel_client_enqueue(int client, struct snd_seq_event *ev,
				  struct file *file, bool blocking)
{
	if (snd_BUG_ON(!ev))
		return -EINVAL;

	if (!snd_seq_ev_is_ump(ev)) {
		if (ev->type == SNDRV_SEQ_EVENT_NONE)
			return 0; /* ignore this */
		if (ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
			return -EINVAL; /* quoted events can't be enqueued */
	}

	/* fill in client number */
	ev->source.client = client;

	if (check_event_type_and_length(ev))
		return -EINVAL;

	struct snd_seq_client *cptr __free(snd_seq_client) =
		client_load_and_use_ptr(client);
	if (cptr == NULL)
		return -EINVAL;
	
	if (!cptr->accept_output) {
		return -EPERM;
	} else { /* send it */
		guard(mutex)(&cptr->ioctl_mutex);
		return snd_seq_client_enqueue_event(cptr, ev, file, blocking,
						    false, 0,
						    &cptr->ioctl_mutex);
	}
}
EXPORT_SYMBOL(snd_seq_kernel_client_enqueue);

/* 
 * exported, called by kernel clients to dispatch events directly to other
 * clients, bypassing the queues.  Event time-stamp will be updated.
 *
 * RETURN VALUE: negative = delivery failed,
 *		 zero, or positive: the number of delivered events
 */
int snd_seq_kernel_client_dispatch(int client, struct snd_seq_event * ev,
				   int atomic, int hop)
{
	if (snd_BUG_ON(!ev))
		return -EINVAL;

	/* fill in client number */
	ev->queue = SNDRV_SEQ_QUEUE_DIRECT;
	ev->source.client = client;

	if (check_event_type_and_length(ev))
		return -EINVAL;

	struct snd_seq_client *cptr __free(snd_seq_client) =
		snd_seq_client_use_ptr(client);
	if (cptr == NULL)
		return -EINVAL;

	if (!cptr->accept_output)
		return -EPERM;
	else
		return snd_seq_deliver_event(cptr, ev, atomic, hop);
}
EXPORT_SYMBOL(snd_seq_kernel_client_dispatch);

static int call_seq_client_ctl(struct snd_seq_client *client,
			       unsigned int cmd, void *arg)
{
	const struct ioctl_handler *handler;

	for (handler = ioctl_handlers; handler->cmd > 0; ++handler) {
		if (handler->cmd == cmd)
			return handler->func(client, arg);
	}

	pr_debug("ALSA: seq unknown ioctl() 0x%x (type='%c', number=0x%02x)\n",
		 cmd, _IOC_TYPE(cmd), _IOC_NR(cmd));
	return -ENOTTY;
}

/**
 * snd_seq_kernel_client_ctl - operate a command for a client with data in
 *			       kernel space.
 * @clientid:	A numerical ID for a client.
 * @cmd:	An ioctl(2) command for ALSA sequencer operation.
 * @arg:	A pointer to data in kernel space.
 *
 * Against its name, both kernel/application client can be handled by this
 * kernel API. A pointer of 'arg' argument should be in kernel space.
 *
 * Return: 0 at success. Negative error code at failure.
 */
int snd_seq_kernel_client_ctl(int clientid, unsigned int cmd, void *arg)
{
	struct snd_seq_client *client;

	client = clientptr(clientid);
	if (client == NULL)
		return -ENXIO;

	return call_seq_client_ctl(client, cmd, arg);
}
EXPORT_SYMBOL(snd_seq_kernel_client_ctl);

/* a similar like above but taking locks; used only from OSS sequencer layer */
int snd_seq_kernel_client_ioctl(int clientid, unsigned int cmd, void *arg)
{
	struct snd_seq_client *client __free(snd_seq_client) =
		client_load_and_use_ptr(clientid);

	if (!client)
		return -ENXIO;
	guard(mutex)(&client->ioctl_mutex);
	return call_seq_client_ctl(client, cmd, arg);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_ioctl);

/* exported (for OSS emulator) */
int snd_seq_kernel_client_write_poll(int clientid, struct file *file, poll_table *wait)
{
	struct snd_seq_client *client;

	client = clientptr(clientid);
	if (client == NULL)
		return -ENXIO;

	if (snd_seq_pool_poll_wait(client->pool, file, wait))
		return 1;
	return 0;
}
EXPORT_SYMBOL(snd_seq_kernel_client_write_poll);

/* get a sequencer client object; for internal use from a kernel client */
struct snd_seq_client *snd_seq_kernel_client_get(int id)
{
	return snd_seq_client_use_ptr(id);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_get);

/* put a sequencer client object; for internal use from a kernel client */
void snd_seq_kernel_client_put(struct snd_seq_client *cptr)
{
	if (cptr)
		snd_seq_client_unref(cptr);
}
EXPORT_SYMBOL_GPL(snd_seq_kernel_client_put);

/*---------------------------------------------------------------------------*/

#ifdef CONFIG_SND_PROC_FS
/*
 *  /proc interface
 */
static void snd_seq_info_dump_subscribers(struct snd_info_buffer *buffer,
					  struct snd_seq_port_subs_info *group,
					  int is_src, char *msg)
{
	struct list_head *p;
	struct snd_seq_subscribers *s;
	int count = 0;

	guard(rwsem_read)(&group->list_mutex);
	if (list_empty(&group->list_head))
		return;
	snd_iprintf(buffer, msg);
	list_for_each(p, &group->list_head) {
		if (is_src)
			s = list_entry(p, struct snd_seq_subscribers, src_list);
		else
			s = list_entry(p, struct snd_seq_subscribers, dest_list);
		if (count++)
			snd_iprintf(buffer, ", ");
		snd_iprintf(buffer, "%d:%d",
			    is_src ? s->info.dest.client : s->info.sender.client,
			    is_src ? s->info.dest.port : s->info.sender.port);
		if (s->info.flags & SNDRV_SEQ_PORT_SUBS_TIMESTAMP)
			snd_iprintf(buffer, "[%c:%d]", ((s->info.flags & SNDRV_SEQ_PORT_SUBS_TIME_REAL) ? 'r' : 't'), s->info.queue);
		if (group->exclusive)
			snd_iprintf(buffer, "[ex]");
	}
	snd_iprintf(buffer, "\n");
}

#define FLAG_PERM_RD(perm) ((perm) & SNDRV_SEQ_PORT_CAP_READ ? ((perm) & SNDRV_SEQ_PORT_CAP_SUBS_READ ? 'R' : 'r') : '-')
#define FLAG_PERM_WR(perm) ((perm) & SNDRV_SEQ_PORT_CAP_WRITE ? ((perm) & SNDRV_SEQ_PORT_CAP_SUBS_WRITE ? 'W' : 'w') : '-')
#define FLAG_PERM_EX(perm) ((perm) & SNDRV_SEQ_PORT_CAP_NO_EXPORT ? '-' : 'e')

#define FLAG_PERM_DUPLEX(perm) ((perm) & SNDRV_SEQ_PORT_CAP_DUPLEX ? 'X' : '-')

static const char *port_direction_name(unsigned char dir)
{
	static const char *names[4] = {
		"-", "In", "Out", "In/Out"
	};

	if (dir > SNDRV_SEQ_PORT_DIR_BIDIRECTION)
		return "Invalid";
	return names[dir];
}

static void snd_seq_info_dump_ports(struct snd_info_buffer *buffer,
				    struct snd_seq_client *client)
{
	struct snd_seq_client_port *p;

	guard(mutex)(&client->ports_mutex);
	list_for_each_entry(p, &client->ports_list_head, list) {
		if (p->capability & SNDRV_SEQ_PORT_CAP_INACTIVE)
			continue;
		snd_iprintf(buffer, "  Port %3d : \"%s\" (%c%c%c%c) [%s]",
			    p->addr.port, p->name,
			    FLAG_PERM_RD(p->capability),
			    FLAG_PERM_WR(p->capability),
			    FLAG_PERM_EX(p->capability),
			    FLAG_PERM_DUPLEX(p->capability),
			    port_direction_name(p->direction));
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
		if (snd_seq_client_is_midi2(client) && p->is_midi1)
			snd_iprintf(buffer, " [MIDI1]");
#endif
		snd_iprintf(buffer, "\n");
		snd_seq_info_dump_subscribers(buffer, &p->c_src, 1, "    Connecting To: ");
		snd_seq_info_dump_subscribers(buffer, &p->c_dest, 0, "    Connected From: ");
	}
}

static const char *midi_version_string(unsigned int version)
{
	switch (version) {
	case SNDRV_SEQ_CLIENT_LEGACY_MIDI:
		return "Legacy";
	case SNDRV_SEQ_CLIENT_UMP_MIDI_1_0:
		return "UMP MIDI1";
	case SNDRV_SEQ_CLIENT_UMP_MIDI_2_0:
		return "UMP MIDI2";
	default:
		return "Unknown";
	}
}

/* exported to seq_info.c */
void snd_seq_info_clients_read(struct snd_info_entry *entry, 
			       struct snd_info_buffer *buffer)
{
	int c;

	snd_iprintf(buffer, "Client info\n");
	snd_iprintf(buffer, "  cur  clients : %d\n", client_usage.cur);
	snd_iprintf(buffer, "  peak clients : %d\n", client_usage.peak);
	snd_iprintf(buffer, "  max  clients : %d\n", SNDRV_SEQ_MAX_CLIENTS);
	snd_iprintf(buffer, "\n");

	/* list the client table */
	for (c = 0; c < SNDRV_SEQ_MAX_CLIENTS; c++) {
		struct snd_seq_client *client __free(snd_seq_client) =
			client_load_and_use_ptr(c);

		if (client == NULL)
			continue;
		if (client->type == NO_CLIENT)
			continue;

		guard(mutex)(&client->ioctl_mutex);
		snd_iprintf(buffer, "Client %3d : \"%s\" [%s %s]\n",
			    c, client->name,
			    client->type == USER_CLIENT ? "User" : "Kernel",
			    midi_version_string(client->midi_version));
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
		dump_ump_info(buffer, client);
#endif
		snd_seq_info_dump_ports(buffer, client);
		if (snd_seq_write_pool_allocated(client)) {
			snd_iprintf(buffer, "  Output pool :\n");
			snd_seq_info_pool(buffer, client->pool, "    ");
		}
		if (client->type == USER_CLIENT && client->data.user.fifo &&
		    client->data.user.fifo->pool) {
			snd_iprintf(buffer, "  Input pool :\n");
			snd_seq_info_pool(buffer, client->data.user.fifo->pool, "    ");
		}
	}
}
#endif /* CONFIG_SND_PROC_FS */

/*---------------------------------------------------------------------------*/


/*
 *  REGISTRATION PART
 */

static const struct file_operations snd_seq_f_ops =
{
	.owner =	THIS_MODULE,
	.read =		snd_seq_read,
	.write =	snd_seq_write,
	.open =		snd_seq_open,
	.release =	snd_seq_release,
	.poll =		snd_seq_poll,
	.unlocked_ioctl =	snd_seq_ioctl,
	.compat_ioctl =	snd_seq_ioctl_compat,
};

static struct device *seq_dev;

/* 
 * register sequencer device 
 */
int __init snd_sequencer_device_init(void)
{
	int err;

	err = snd_device_alloc(&seq_dev, NULL);
	if (err < 0)
		return err;
	dev_set_name(seq_dev, "seq");

	scoped_guard(mutex, &register_mutex) {
		err = snd_register_device(SNDRV_DEVICE_TYPE_SEQUENCER, NULL, 0,
					  &snd_seq_f_ops, NULL, seq_dev);
	}
	if (err < 0) {
		put_device(seq_dev);
		return err;
	}
	
	return 0;
}



/* 
 * unregister sequencer device 
 */
void snd_sequencer_device_done(void)
{
	snd_unregister_device(seq_dev);
	put_device(seq_dev);
}
